The invention relates to a method for correcting the water permeability of a subterranean formation penetrated by a well bore. In one aspect this invention relates to prolonging or reestablishing mobility control and/or plugging of a subterranean formation penetrated by a well bore. In another of its aspects this invention relates to the gelation of residual ungelled polymer solution in an underground formation.
There are various techniques known to the art for treating underground formations with ungelled polymer solutions to correct the water permeability of the formations. Known processes include the flooding of the formation with ungelled polymer, the injection of partially gelled polymer into a formation, and the injection of ungelled polymer in combination with the injection of gelling agent either simultaneously or in alternating slugs. In most of these processes there is residual ungelled polymer in the formation when production is resumed through the well bore. It is an object of this invention advantageously to use this residual ungelled polymer in a subsequent retreatment of the underground formation to prolong or to reestablish mobility control of the formation. Stated in another way, it is also an object of this invention to provide a method for controlling the mobility and/or plugging of a subterranean formation penetrated by a well bore which has been previously treated with a partially gelled polymer or an ungelled polymer solution.
Other objects, aspects, and the various advantages of this invention will become apparent upon reading this specification and the appended claims.